Not sure how vimeo deals with 4k clips but on display it will be max 720p if you have a free or plus account, when you have a pro account you have 1080p. 4K display I have not heared of if they will support it in the near future but that probably also will only be for the pro accounts.

I would first convert to a 720p file following these guidelines (https://vimeo.com/help/compression) and then replace your video, it should look a lot better then the SD file you have now.

You could put it on youtube who has higher rez, up to 4k viewing options.